Generally, a cancer is caused in an organ of a patient, such as a liver. The cancer is treated by a non-surgical operation or a surgical operation.
However, in case of the surgical operation, the skin of the patient must be cut over a large area prior to removal of a lesion from the patient body. Therefore, the surgical operation undesirably leaves a large and ugly scar on the skin of the patient and mars the appearance of the patient. Furthermore, the surgical operation undesirably forces the patient to spend a lengthy period of time for recovery.
Furthermore, when the cancer relapses in the organ of the patient, the surgical operation must be executed again. Thus, the repeated surgical operation undesirably forces the patient to undergo repeated severe pain, in addition to paying additional money. Furthermore, the repeated surgical operation is attended with danger.
To avoid the above-mentioned problems of the surgical operation, various types of non-surgical operations, such as a transarterial chemoembolization, a percutaneous ethanol injection, a general chemotherapy for cancer, a local thermotherapy and etc., have been used. The local thermotherapy is most effective in the above-mentioned non-surgical operations.
In the local thermotherapies, there are a high frequency thermotherapy, a microcauterization, a laser cauterization and etc. In the above-mentioned local thermotherapies, the high frequency thermotherapy has been most effectively used.
The high frequency thermotherapy is a therapy to cauterize and necrotize, for example, cancer tissues caused in the organ of a patient, such as the liver, using high frequency heat without cutting over the skin of the patient prior to the removal of the cancer tissues from the patient body.
As shown in FIG. 1, a conventional electrode device for the high frequency thermotherapy comprises a main casing 5, an electrode needle 6 which is coupled to a first end of the main casing 5, and an electrode cable 4 which is coupled to a second end of the main casing 5 to supply a high frequency wave to the electrode needle 6. The conventional electrode device further comprises a cooling tube 3 which is coupled to the second end of the main casing 5 to circulate cooling water to or from the electrode needle 6, thus preventing the electrode needle 6 from being damaged by the high frequency heat.
The electrode needle 6 typically includes a conductive needle part 6a which is defined at a predetermined part of a tip of the electrode needle 6, and an insulating needle part 6b which is defined at a remaining part of the electrode needle 6 except for the conductive needle part 6a. 
At this time, preferably, a plurality of electrode needles 6, respectively having various conductive needle parts 6a of lengths different from each other, are prepared. Thus, during the thermotherapy operation, one of the various electrode needles 6 is selectively coupled to the main casing 5 to correspond to a size of the lesion of a patient. That is, the length of the conductive needle part 6a must be longer than a depth of a part of the lesion through that the tip of the electrode needle 6 passes. Therefore, the conductive needle part 6a cauterizes the lesion using the high frequency heat in a wider range than the lesion, thus firmly executing the operation.
The operation of the conventional electrode device for the high frequency thermotherapy is as follows. As shown in FIG. 2, the electrode needle 6, having the conductive needle part 6a corresponding to the size of the lesion 100 of the patient, is coupled to the main casing 5. Thereafter, the electrode cable 4 connects the electrode needle 6 to a high-frequency generator which is not shown. An electrode pad 2, which is in contact with a body of the patient, is connected to the high-frequency generator through an additional electrode cable.
Thereafter, the cooling tube 3, which is coupled to the main casing 5, is connected to a cooling pump (not shown) to circulate cooling water to or from the electrode needle 6.
In the above state, the electrode needle 6 is inserted into the lesion 100, such as the cancer tissues of the organ of the patient. Thereafter, the high frequency wave is supplied to the conductive needle part 6a of the electrode needle 6, except for the insulating needle part 6b, from the high-frequency generator. Thus, the lesion 100 is cauterized, and thus, necrotized by high frequency heat.
After the operation of cauterizing the lesion 100 is completed, the electrode needle 6 is removed from the body of the patient.
However, the conventional electrode device for the high frequency thermotherapy is problematic as follows.
First, because the length of the conductive needle part 6a of the electrode needle 6 is fixed, the conventional electrode device forces a user to purchase a plurality of electrode needles 6, of which the conductive needle parts 6a respectively have different lengths, and selectively use one of the plurality of electrode needles 6 according to a size of the lesion 100.
That is, the user must purchase the various electrode needles 6, of which the conductive needle parts 6a respectively have different lengths, for example, 1 cm, 2 cm, 3 cm and etc., prior to selectively using one of the various electrode needles 6. Therefore, the conventional electrode device forces the user to pay excessively, in addition to causing inconvenience for the user.
Second, in case that the thermotherapy operation is repeatedly executed several times on the lesion 100, or in case that the thermotherapy operation is executed while changing a plurality of electrode needles 6, the electrode needles 6 must be repeatedly inserted into and removed from a target portion of the patient body with the lesion 100. Therefore, the conventional electrode device causes severe pain and harm to the patient while the electrode needle(s) repeatedly prick(s) the target portion of the patient body.
Third, in the conventional electrode device including the electrode needle 6 of which the conductive needle part 6a has a predetermined fixed length, it is very difficult to control the range of cauterizing the lesion 100. That is, while the lesion 100 is cauterized by the electrode needle 6 with the conductive needle part 6a of the predetermined fixed length, the conventional electrode device does not have any means to control the range of cauterizing the lesion 100, except for controlling the power of the high frequency wave. Therefore, the electrode needle 6 must be repeatedly inserted into the lesion 100 through several parts of the patient body to cauterize the whole lesion 100